Mandrel for use in twisting rectangular tubing



2,868,266 MANDREL. FOR USE IN TWISTING RECTANGULAR TUBING Filed Nov. 4, 1953 Jan. 13, 1959 F. J. FUCHS, JR

2 Sheets-Sfieet 1 INVENTOII 2126M w flifi 01;,

BY Q. I

. ATTORNEY Jam J13, 1959 F. J. FUCHS, JR

MANDREL FOR USE IN TWISTING RECTANGULAR TUBING Filed Nov. 4, 1955 INVENTOR 2 Sheets-Sheet 2 fiazzadsJZZwA-gfi; B) (La ATTORNEY United States Patent MANDREL FGR USE IN TWISTING RECTANGULAR TUBING Francis J. Fuchs, Jr., Winston-Salem, N. C., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application November 4, 1953, Serial No. 390,138

4 Claims. (Cl. 153-63) the ends of the tubing bear a symmetrical cross-like unv displaced relationship to one another and to mandrels for effecting twists wherein the ends of the tubing are rotated and also displaced horizontally and/or vertically relative to one another.

In the manufacture of electrical assemblies utilizing rectangular wave guide tubing, it frequently becomes necessary to align the end-of a first tube with the end of a second tube or similar structure which is rotated and also linearly displaced relative to the end of the first tube.

Accordingly, it is an object of the present invention to provide a flexible mandrel to permit twisting of a noncircular tube which supports the interior of the tube during twisting.

It is a further object of the present invention to provide a mandrel for use in supporting the interior of a non-circular tube which is subjected to a simple rotary or straight twist.

It is still another object of this invention to provide a mandrel which may be used to support the interior of a non-circular tube when subjected to a straight twist or to a twisting operation wherein the ends of the tube to be twisted are rotated and also linearly displaced by predetermined vertical and/or horizontal distances relative to one another.

In accordance with the above objects a mandrel is provided for use in twisting a tube having an internal cross-sectional configuration other than circular and comprising a stem, a plurality of fiat laminations having peripheral configurations corresponding to the internal cross-sectional configuration of the tubing, each of said laminations also having a first aperture located substantially at the center of each lamination and one or more apertures smaller in size than the first aperture and located near the periphery of each lamination, a rigid center or core rod secured at one extremity to the stem and passing through the first apertures whereby the laminations may rotate about the rod, means connected to the free end of the rod for retaining the laminations thereon, resilient wires positioned in the smaller apertures to maintain the laminations in mutual alignment in the absence of a twisting force, and means to retain the wires in the smaller apertures.

A complete understanding of the invention may be had from the following detailed description when taken in conjunction with the following drawings, wherein:

Fig. 1 is a front elevational view, partially in cross section, showing a mandrel for effecting a straight twist in a rectangular tube;

Fig.- 2 is a top plan view, partially in cross section, of the mandrel shown in Fig. 1;

Fig. 3 is an end elevational view of the straight twist mandrel taken on line 3-3 of Fig. 1;

2,868,266 Patented Jan. 13, 1959 Fig. 4 is atop plan view of a twisted modified mandrel, particularly adapted for effecting a displaced twist in rectangular tubing;

Fig. 5 is a. front elevational view, partially in cross section, of the mandrelshown in Fig. 4;

Fig. 6 is an end elevational view of the modified mandrel taken on line 6-6 of Fig. 5; and

Fig; 7 is an end view of the modified mandrel showing a possible displacement of the ends of the mandrel after a degree rotation.

Referring now to the drawings wherein like reference numerals refer to the same elements throughout the several views, and more particularly to Fig. 1, the numeral. 12 designates generally a mandrel having a rigid stem provided with a threaded aperture 14 for connection to a reciprocable mandrel. shaft 15. A rigid center rod 16 is secured in anaperture 17 in the free extremity of the stem by means of pins 18. A plurality of fiat, rectangular laminations 19 having the edges and corners thereof slightly rounded (Fig. 3) are provided with central apertures 20 by means of which the laminations 19 are mounted on the center rod 16 .by passing the rod through the central apertures 20. A tapered terminal plate 22 having a: centrally located aperture .23 is mounted near the free extremity .of the center rod 16 for abutting an end lamination 19. The free extremity of the center rod 16 isprovided with a threaded aperture 24 for receipt therein of a bolt 25 which, together with a Washer 26, serves to retain the laminations 19 in mutually sliding relationship with respect to each other upon the center rod 16. Each of the laminations 19 is provided with a non-centrally or eccentrically located aperture 27. A resilient rod or wire 28 extends through the eccentric apertures 27 in the laminations 19, through an aperture 21 in the terminal plate 22 and into an aperture 29 in theiforward portion of the rigid stem 13 wherein the resilient rod.2 8 is secured by means of set screws 30-operating in apertures 32 in the rigid stem- 13. A portion of the resilient rod 28 projects forwardly to the right (Figs. 1 and 2) beyond the free extremity of the rigid center rod 16 and the plate 22. and is provided with a spherical ball or contact member 33 mounted on the free extremity of the resilient rod. A helical spring 34 is mounted about the forwardly projecting portion of the resilient rod 28 and bears upon the ball contact member 33 and the terminal plate 22.

In operation, to effect a straight or simple rotary twist in a rectangular tube, the above described mandrel 12 is mounted, by means of the threaded connection 14 in the rigid stem 13, on thesrec iprocable mandrel shaft 15, and the mandrelis fedforwardly by suitable means (not shown so that the laminated portion of the mandrel is positioned inside the rectangular tubing to be twisted. Upon application of a suitable t-wistingforce, as by the invention disclosed in co-pending application Serial No. 390,224,.filed on November 4, 1953, the laminations19 rotate about the center rod 16 in conformance with the changing shape of the tube thereby supporting the interior of the tube. The rounded edges and corners of the laminations prevent the formation of scratches on the interior of the tube as the laminations move therein. Thehmandrel lz is then removed from the tubing whereupon the twisted resilient rod 28 returns the laminations 19 to their oriented. positions. During the twisting operaiton the resilient rod 28 is subjected to a twisting force which results in a lengthening of the .path of travel of the resilient rod through a given longitudinal section of the laminations, which increase in length is provided for by the portion of the resilient rod extending forwardly beyond the free end of the center rod 16. The shortening of the forwardly projectingportion, of .the

resilient rod results in a compression of the helical spring 34 which, upon removal of the twisting force, assists the resilient rod 28 in returning the laminations 1-9 to their oriented positions.

Figs. 4, 5, 6 and 7 disclose a modification of the present invention particularly adapted to effect displaced twists in rectangular tubing. The numeral 35 designates generally a mandrel having a first stem member 36 provided with a threaded aperture 37 for connection to the reciprocable mandrel shaft 15 and having a projecting tongue member 38 which is provided with a circular aperture 39. A second stem member 40 is provided with projections 42 having circular apertures 43 for pivotable connection by means of pivot pin 44 with the tongue member 38 of the first stem member 36. The second stem member 40 is further provided with a threaded aperture 45 and a beveled rectangular end plate 46. With the exception of'the end plate 46, the vertical and horizontal dimensions of all parts of the first and second stem members 36 and 40 are smaller than the corresponding dimensions of laminations 48, thereby providing a space 54 between the stern members and the interior surfaces of a tube 55.

A rigid core rod 47 is threadedly connected to the second stem member 40 at its threaded aperture 45. A plurality of flat rectangular laminations 48 are provided having circular apertures 49 therein which are ofiset from the center of the laminations and by means of which the laminations 48 are mounted upon the core rod 47 for rotation thereabout. The free extremity of the core rod 47 is provided with a threaded aperture 50. A beveled terminal plate 52 is provided with an aperture 53 for mounting near the free extremity of the core rod 47 and for abutting an endmost lamination 48. A washer 56 is provided for abutting the forward or right-hand surface (Figs. 4 and of the terminal plate 52 and a bolt 57 is threadedly engageable with the aperture 50 in the free extremity of the core rod 47 and abuts the washer 56 for retaining the laminations 48 in mutually sliding relationship with respect to each other upon the core rod 47.

The diameter of the offset aperture 49 of each lamination 48 is greater than the diameter of the core rod 47 by a horizontal clearance C and a vertical clearance C (Fig. 6), which clearances are functions (1) of the displacement D (Fig. 4) of the ends of the twisted tubing and (2) of the ratio of the lengths of the untwisted and the twisted portions of the mandrel 35.

The laminations 48, the terminal plate 52 and the end plate 46 are provided with apertures 58, 59 and 60, respectively, which are smaller than the offset apertures and through which are passed resilient rods or wires 62 which are fixed to the terminal plate 52, as by soldering. The wires 62 are not fixed to the end plate 46 but instead are unsecured and project rearwardly to the left (Fig. 5) beyond the smaller apertures in the end plate 46 for a desired distance.

In operation, to effect a displaced twist in a tube, the tube 55 is mounted with its extremities held by a fixed clamp 63 and an eccentrically mounted rotatable clamp 64 (Figs. 4 andS). An apparatus for mounting and twisting a non-circular tube is also disclosed in the previously mentioned co-pending application. The first stem member 36 is then attached to the reciprocable mandrel rod 15 and the assembled mandrel 35 is inserted into the bore of the tube 55. At the beginning of a twisting operation the core rod 47 rests adjacent one side of the OE- set apertures 49 in the laminations 48 (Fig. 6).

Upon application of a suitable twisting force, wherein the free end of the mandrel 35 is twisted through the desired angle, for example 90 1 degrees, and is simultaneously displaced by horizontal and/or vertical distances resulting in a total displacement equal to a desired linear displacement D, (Fig. 4) the core rod 47 pivots about the point P located at the intersection of the longitudinal axis of the core rod and the right-hand face (Fig.

4) of the end plate 46. This movement of the core rod 47 results in a lateral shifting of the slightly flexible mandrel shaft 15 and of the associated stem member 36 by a distance S and a lateral tilting movement of the second stem member 40, the laminations 48 and the terminal plate 52 (Fig. 4).

Upon completion of the twisting operation, the mandrel 35 is withdrawn from the twisted tube 55 and the resilient wires 62 return the laminations 48 to their normal oriented positions on the core rod 47.

Figs. 4 and 5 show, in the area bounded by the dashdot lines, a portion of the twisted tube in which the mandrel is inserted during the twisting operation.

Manifestly, the present invention is not restricted to a mandrel for twisting rectangular tubing as described in the preferred embodiments, but mandrels using the disclosure of this invention could be devised for twisting any tubing having any internal cross-sectional configuration other than circular.

It is to be understood that numerous other modifications could be made without departing from the spirit and scope of the invention.

What is claimed is:

1. An articulated mandrel for use in twisting noncircular tubing, which comprises a stem, a rigid center rod secured at one end to the stem, a plurality of laminations having peripheral configurations corresponding to the internal cross section of the tubing, said laminations being thin and flat so as to lend a substantially continuous support to the inside of the tubing during the twisting thereof and each lamination having a non-central aperture and a central aperture, by means of which central aperture each lamination is mounted rotatably on the center rod in sliding contact with adjacent laminations, a tapered terminal plate having a non-central aperture and a central aperture, by means of which the terminal plate is rotatably mounted on the center rod near the free end thereof, a resilient rod extending through non-central apertures of the laminations and the terminal plate and having one end thereof secured to the stem and the other end normally projectingbeyond the terminal plate, a stop member secured to the free end of the resilient rod, and spring means mounted between the stop member and terminal plate cooperating with the resilient rod to urge the laminations into mutual alignment.

2. An articulated mandrel for supporting the interior of non-circular tubing during twisting and linear displacing operations, which comprises a stern, a core rod secured to the stem, a plurality of thin, flat laminations having peripheral configurations corresponding to the internal cross section of the tubing, each of said laminations being provided with an aperture for rotatably mounting the laminations on the core rod, said apertures being larger than the diameter of the core rod by an amount such as to allow a desired displacement of the tubing and being olfset from the centers of the laminations to allow for the displacement of the tubing during the deforming operation, means to retain the laminations on the rod, and resilient means tending to maintain the laminations in mutual alignment.

3. An articulated mandrel for supporting the interior of non-circular tubing during twisting and linear displacing operations, which comprises a first stem member, a second stem member pivotally connected to the first stern member for lateral movement with respect thereto, a rigid core rod secured at one end to the second stem member, a plurality of thin, flat laminations having peripheral configurations corresponding to the internal cross section of the tubing, each of said laminations having a plurality of non-centrally positioned perforations and an aperture therethrough, each of said apertures being larger than the diameter of the core rod by an amount such as to allow a desired displacement of the tubing and being offset from the center of the laminations to allow for the displacement of the tubing during the deforming operation, said l'aminations being mounted rotatably on the core rod by projecting said core rod through the apertures, a perforated end plate connected rigidly to the second stem member .for abutting one end lamination, a perforated terminal plate mounted rotatably on the core rod abutting the other end lamination, means to retain the terminal plate and the laminations on the core rod, and resilient wires secured to the terminal plate and projecting through the perforations in the terminal plate, the laminations and the end plate, said resilient wires tending to maintain the laminations in mutual alignment.

4. An articulated mandrel for supporting the interior of tubing during twisting and linear displacing operations, which comprises a stem, a rigid rod secured to the stem, a plurality of thin, flat laminations having peripheral configurations conforming to the internal cross section of the tubing and being mounted rotatably on the rod, said laminations being provided with apertures ofiset from the centers of the laminations, each of said apertures being larger in diameter than the rod by, an amount such as to allow for a relative radial movement therebetween, means to retain the laminations on the rod, and means tending to maintain the laminations in mutual alignment.

References Cited in the file of this patent UNITED STATES PATENTS 279,573 Leaycraft "June 19, 1883 650,049 Lynch May 22, 1900 757,592 Atwood Apr. 19, 1904 1,534,314 Heintz Apr. 21, 1925 1,826,077 J'ohnson Oct. 6, 1931 1,826,403 OBrien Oct. 6, 1931 1,856,597 Stjarnstrom May 3, 1932 1,958,982 Wintercorn May 15, 1934 2,044,322 Oliver et al June 16, 1936 2,399,892 Sato May 7, 1946 2,422,953 Davies et a1. June 24, 1947 Y FOREIGN PATENTS 17,807 Great Britain Sept. 24, 1895 532,068 France Nov. 7, 1921 OTHER REFERENCES The disclosure on page 208 of the book, Microwave Transmission Circuits, edited by George L. Ragan, published by the McGraw-Hill Book Company, Inc., in 1948 and copyrighted on May 21, 1948. 

